Photolytic pumping of the HgCl35(B→X) laser has been demonstrated. Oscillation at 557.6 and 558.4 nm was obtained by irradiating HgCl2vapor and helium with incoherent Xe*2emission at 172 nm from an e‐beam‐excited xenon plasma. Also, by photodissociating HgCl2with ArCl* (175 nm) fluorescence, the HgCl(B) state radiative lifetime was determined to be 22.2±1.5 ns.